In filling a content, for example a liquid, into a conventional plastic package with a fastener by using an automatic plugger, an inlet portion of the package is heat-sealed leaving a bottom portion of the package open, the content is filled from the bottom portion and the bottom portion is heat-sealed to ensure complete sealing of the packing and protect the fastener. For easy opening, a notch for cutting with scissors, perforation, or tape for tearing is provided at an upper portion of the heat-sealed inlet portion.
As described above, the content has to be filled from the bottom portion of the conventional plastic package with the fastener to prevent the content from attaching to the fastener and catching in groove of the fastener, and to keep the package quality from being degraded by the contents which are tacky or putrescent and colored.
On the other hand, a large volume plastic package such as a gusseted bag, a standing pouch, a laminated paper pack, a thermoplastic resin and the like are rarely used as a plastic package with a fastener because the contents cannot be filled from a bottom portion in view of the structure thereof and have to be filled from an inlet side of the package, and the fastener becomes contaminated. Accordingly, most conventional plastic packages with a fastener are flat bags having a small volume.
An easy to open package without a fastener has problems in terms of its transportation stability, shelf-life or the like because an inlet portion thereof is easily opened by internal pressure, thus limiting its usage. This phenomenon is especially apparent in a large volume package having a large ratio of content volume/packing material area. Yet, durability against internal pressure and easy to open characteristic cannot be compromised.
Consequently, there is a need for a large volume plastic package with a fastener having a large ratio of content volume/packing material area such as a gusseted bag, a standing pouch, a paper pack or the like, while being easy to open, capable of being resealed and not easily opened at the inlet portion by internal pressure.
An object of the present invention is to provide a plastic package with a fastener having excellent filling, opening and resealing characteristics even if the content is liquid and excellent pressure resistance that enables filling a large volume of contents, as well as, excellent transportation stability and shelf-life.